Conventionally, as mouse pads (the sheet placed under a mouse during VDT operation), soft flexible sheets, woven fabrics, knitted fabrics, non-woven fabrics, foamed materials or laminates thereof have been used. Although they make a track ball roll smoothly, when the track ball is stained for some reason such as after a long use or with human sweat in the summer season, it does not roll smoothly and must be cleaned to recover smooth rolling.